Piston



July 1, 19.30. F. J. KENT I 11,768,608

PISTON Filed June 27, 1927 2 Sheets-Sheet l INVENTOR July 1, 19399 J, T 1,768,608

PISTON Fild June 27. 1927 2 Sheets-Sheet 2 A I ZEEX/ A I .llll

Patented. July 1, 1930 Z U ITED STA TESV AT NT OFFICE FRANK 3.1mm, or moiv'rcnam, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS,

. .OHIO' PISTON without expanding diametrally to such an pansion than the'metal of which the piston {solely or primarily. 30

extent as to cause unsatisfactory operation of the piston in a cylinder, where, as is now common, the metal of which the cylirrder is made has a smaller coeflicient of exis made. 1 p p 7 Another object is to provide a piston" so constructed, or having means incorporated therein in such manner, that all portions of the 'skirt ma expand as fully and freely.

as though the s zirt were not confined in the c linder and yet without increasing the frictional drag between the thrust faces of the skirt and the cylinder during and after such expansion. 0

Another object is to provide a piston formed wholly or in the main of a material of a comparatively high coeflicient of expansion, soconstituted that skirt portions may expand fullyand freely il "a direction to, increase the axial-length of- ,the piston Another object'isto provide a piston including a head and a skirt, with the skirt so'constructed and so inter-connected that,

while the skirt is expandible and contractible in accordance with temperature conditions, the skirt will not change in girth on a riseof temperature.

Another object is to provide a piston including a head and a skirt, with the skirt so constructed and so connected to the head that,.while the skirt is expandible and contractible in accordance with temperature conditions, the skirt will not change in girth on a rise of temperature.

Another object is to rovide a' iston includin a head and a s irt, the s 'rt being expan ible and 'contractible in accordance with temperature conditions, in combination with means for causing a contraction of the skirt when the temperature is raised. Various other objects and advantages of Application filed .Tune 27,-

1927-. Serial No. 201,650.

the invention than those hereinabove mentioned .will be speoificall pointed out or wi1l be apparent hereina er in the course of the below detailed description of the forms of the invention shown, in-the accompanying drawings, as preferred ones of the various possible embodiments of the,invention; it being understood, naturally, that such forms are merely illustrative of some of the many possiblecombinations and arrangements of parts well calculated to attain the objects of the invention, andhence said detailed description of such forms is not to be taken as at all defining or limiting the invention itself. That is to say, the scope of protection contemplated is of course to be taken from the'appended claims,-

interpreted as broadly as is consistent with, the prior art.

In the accompanying drawings Fig. 1 shows, partially in elevation, and partially in section, one form of the invention;

Fig. 2 is an axial section, taken 2-2 of Fig. 1;

Fig. 3 is a transverse section, taken on line 33 of Fig. 1;

Fig. 4 is an axial section, taken on line 4 4 of Fig. 2; a

ig. 5 is a plan view of a thermostatic on line TO THE- CLEVELAND TRUST GOMIEANY, OF CLEVELAND, OHIO, A COBPORATION 0]! element constituting a part of the form shown'in- Figs-1 to 4;

Fig. 6 is an. axial section, illustrating another form of the invention;

Fig. 7 is a view similar to Fig. 6, but taken on the line 77 of Fig. 6; and

Fig. 8 is aview' similar to Fig. 4, but' showing a modification of the form of the invention shown in Figs. 1 to 4.

Similar reference characters refer to similar parts throughout.the several views of the drawings.

Referring to the piston, which is preferably formed of light weight material such an aluminum alc the drawings more specifically, in all of the'illustrated embodiments,

loy, comprises a head 10 and a skirt 11. The

head is in the usual cylindrical form having piers 12 which extend downwar the conventional manner and which at their lower ends carry pin bosses 13.

The skirt, the upper part of which is insulated from the head in any'desired manner, as by providing an air gap 14: extending around the greater part of the circumference of the piston, is in the formof a cylindrical spiral as the result of providing a spiral groove or grooves, in the present case a single such groove, marked 15.

In all the illustrated embodiments also, the spiral skirt element is connected at its upper" end with one of the piers 12; while the parts of such spiral element beyond and below the last mentioned pier, define a tubular housing surrounding and spaced from the other pier and thetwo pin bosses. In order to insert the pin (not shown) this tubular housing, that is, the skirt, may have cut-outs 16 opposite one of the bosses and defining a circle concentric with the pin receiving hole in the boss.

Referring now more particularly to the form of the invention shown in Figs. 1 to 5,

pairs of upper and lower lugs 17 are formed on the inside of the skirt, as shown in Figs. 2 and 3, and two oppositely disposed sets of such lug pairs are provided as shown in Figs. 3 and 4. Spanning each upper and lower pair of lugs, at each sideof the skirt, and mounted in the lugs as clearly shown in the drawings, is a thermostatic element 18. These elements are preferably bowed as shown; and may be made up in the conventional way of a plurality of strips of metals of dissimilar coefficients of expansion. The thermostatic elements are-so constructed that on raising the temperature thereof, they tend to expand longitudinally, that is, to assume a curvature of greater radius. lt will be clear that these thermostats may be so designed and incorporated that they will function to elongate the spiral skirt as desired under predetermined operatin temperatures; thereby to permit the s irt to maintain a constant diameter at different temperatures and yet freely and fully expand in all portions on an increase internperature; and, obviously, the arrangement may be such that on the piston or any par ticular part of the piston reaching a certain predetermined temperature, the piston will nested in an annular recess within the head 10 located above an internalfiange or ledge 10. Bolted to the central'point of the element 18 and depending therebelow, and arranged at right anglesthereto, is a crossbridge 20. Thrust rods 21 are secured at their upper ends in the opposite extremities of the bridge. These rods diverge in. a downward direction, and their lower ends are secured in lugs 17 on the inside of the lower end. of the skirtll. The thermostatic element 18 in the present case, is so constructed that on raising the temperature thereof, it tends to assume a curvature of smaller radius, that is, to exert a down push on, bridge 20. According to this construction, an undesirable rise in temperature of the skirt 11 will result in a downwardthrust of rods 21, and thereby cause an axial enlargement, of the spiral constituting the skirt; so that, according to the design of the parts, the skirt will be caused to maintain a constant diameter at different temperatures or to have its girth contracted on any particular part of the piston reaching a certain predetermined temperature.

Comparing the forms of the invention shown in Figs. 1 and 7, and which have ust beenv described it is pointed out that the prolongation thrustagainst the lower portion of the piston has in the case of the form of Fig. 7, its reaction point against the head, and not against the upper portion of the skirt, as in the case of the form of Fig. 1, and by virtue ,of this distinction, the form of Fig. 7 is at present belleved to represent a preferable construction over that shown in Fig. 1. i

However, referring to Fig. 8, t will be noted that the type of embodiment of Fig. 1, may also be'carriedout practicably to locate said reaction point in the head 10. In Fig, 8, as in Fig. 1, a pair of thermostatic elements are employed. Theseelenients of Fig. 8, marked 18, are precisely similar to the elements 18 of Fig. 1,.except that the elements 18 are somewhat longer and their upper ends areanchored inupper lugs-17", within the head 10.

Inasmuch as many changes could be made in the above constructions, and many apparently widely different embodiments of the invention could be made without departing from the scope thereof, it is intended thatall matter contained in the abeve description or shown in the accempanyrng drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language contained in the following claims is intended'to cover allthe generic and specific features of the invention herein described, and all statements ofthe scope of the invention which, as a matter of language, might be said'to fall therebetween.

1. .As a new article of manufacture, a

piston including a head, and a skirt having a spiral slot extending completely aroun the skirt and throughout the length thereof.

2. As a new article of manufacture, a piston including a head, and. a skirt having a spiral slot extending throughout the length thereof "and having a plurality of convolutions,'the lower end of the slot opening into the lower edge of the skirt.

3. A piston having ahead, a skirt element of spiral form joined at one end to the head, said element being flexible radially and axially and havinga bearin face which conforms to. a cylindrical sur ace, and thermal- 1y controlled means connecting the head and skirt element for exerting an axial thrust on said skirt element at a point spaced from r the head to cause expansion of the skirt to manifest itself in an axial direction primarily.

- 4:. A piston comprising a head, a skirt element joined at one end to the head and having its ends offset circumferentially, said element being flexible radially and axially and having an exterior bearing face which conforms to a cylindrical surface, and means acting on portions of the skirt element spaced axially from the head for holding the skirt. element against increase in girth when expanded by heat.

5. A piston comprising a head, a skirt element joined at one end to the head and having its ends offset .circumferentially, said elementbeing flexible radially and axially and having an exterior bearing face which conforms to a cylindrical surface, and thermally controlled means connecting the head and skirt element for exerting an axial I thrust on said skirt element at a point 40 spaced from the head to cause expansion of the skirt to manifest itself in an axial diirection primarily.

In testimony whereof I afiix my signa- Wm. FRANK J. KENT. 

